First of all, I have already read Can “an” and “année” be used interchangeably, is there a difference in meaning? , but I haven't a found to my answer in it.
I have read the following sentence in Duolingo:
Vous enseignez ici depuis plusieurs années. (= You have been teaching here for several years)
DeepL translator agrees with this translation.
However, for days instead of years, DeepL translator translates "You have been teaching here for several days" to "Vous enseignez ici pendant plusieurs jours". Are those translations correct? If so, why an/année and jour/journée are not used consistently in those sentences? Would "plusieurs ans" and "plusieurs "journées" be correct in those sentences too?